Word Problems

An actor invests some money at 7%, and 47,000 more than four times the amount at 12% The total annual interest earned from the investment is 49640. How much did he invest in each amount?
He invested ___ at 7% and ___ at 12%

A pharmacist wishes to mix a solution that is 7% minoxdil. She has on hand 80ml of a 1% solution and wishes to add some 9% solution to obtain the desired 7% solution. how much 9% solution should she add?

how many gallons of 50% anti-freeze solution must be mixed with 100 gallons of 30% anti-freeze to get a mixture that is 40% anti-freeze?